An internal combustion engine generally includes one or more combustion chambers that house a combustion process to produce mechanical work and a flow of exhaust. Each combustion chamber is defined by a cylinder, a top surface of a piston, and a bottom surface of a cylinder head. Air or an air/fuel mixture is directed into the combustion chamber by way of intake ports in the cylinder head, and a resulting exhaust flow is discharged from the combustion chamber by way of exhaust ports also in the cylinder head. Valves are located within bores associated with the intake and exhaust ports and sealed against valve seat inserts to selectively allow and block the flows of air and exhaust through the intake and exhaust ports.
Traditional valve seat inserts are pressed into their respective bores and then, machined to specific tolerances, allowing the valves to seat properly. While successful, this machining process may not be cost effective. In particular, machining the valve seat inserts after installation into their respective bores can require additional tooling and be difficult to perform in the field.
During engine operation, cylinder heads, valves, and valve seat inserts are exposed to high stresses and temperatures. And, over time, these high stresses and temperatures can cause excessive wear of the cylinder head, the valves, and the valve seat inserts.
One solution to the high stresses and temperatures described above is disclosed in U.S. Pat. No. 5,745,993 (“the '993 patent”) issued to Adachi et al. on May 5, 1998. The '993 patent describes a reciprocating machine having a cylinder head including intake and exhaust flow passages that are controlled by intake and exhaust poppet-type valves. Each valve has a head portion that cooperates with a respective valve seat formed at lower ends of the intake and exhaust flow passages. The cylinder head utilizes a valve insert ring to form the valve seat that is press-fit within each flow passage. One or more water jackets are formed within the cylinder head and provide cooling for the cylinder head, the valves, and/or the valve insert rings.
Although the water jackets of the '993 patent help to provide some cooling for the valves and the valve insert rings, it may still be less than optimal. Specifically, the water jackets of the '993 patent are located a distance from the valve insert rings, and this distance may limit the amount of heat that can transfer from the valve insert rings and their respective valves to coolant in the water jacket. Additionally, the valve insert rings of the '993 patent are first inserted into their respective positions and then, machined into place. This machining process may be expensive and limit remanufacturing options.
The cylinder head assembly of the present disclosure solves one or more of the problems set forth above and/or other problems with existing technologies.